René Descartes viewed the world with a cold analytical logic. He viewed all physical bodies, including the human body, as machines operated by mechanical principles. His philosophy proceeded from the austere logic of "cogito ergo sum" -- I think therefore I am.

In mathematics Descartes chief contribution was in analytical geometry.

Descartes' portrait is quadrisected by the axes of his great advance in analytical geometry: what has come to be known as the Cartesian plane. It enabled an algebraic representation of geometry.

Descartes saw that a point in a plane could be completely determined if its distances (conventionally 'x' and 'y') were given from two fixed lines drawn at right angles in the plane, with the now-familiar convention of interpreting positive and negative values.

Conventionally, such co-ordinates are referred to as "Cartesian co-ordinates".

Descartes asserted that, similarly, a point in 3-dimensional space could be determined by three co-ordinates.